A solitary goal from Riyad Mahrez ensured Leicester City maintained their 100 per cent Champions League record with a 1-0 win over Copenhagen at the King Power Stadium to leave them on the brink of the knockout stages.
Mahrez, recalled to the starting line-up having begun Saturday's 3-0 Premier League loss to Chelsea on the bench, was in the right place to capitalise on Islam Slimani's header and break the deadlock in the 40th minute.
His mid-air flick proved enough to secure Claudio Ranieri's side a third straight win in their debut campaign in the competition and they sit five points clear at the top of Group G having yet to concede a goal in Europe.
Leicester - who saw Slimani have a second-half effort ruled out for offside - now have one more point in Europe than they do after eight games of their title defence in England.
Porto beat Club Brugge 2-1 in the pool's other contest and Leicester will now head to Denmark for the return fixture on November 2 knowing a win will secure them a place in the next round.
Copenhagen suffer their first loss in any competition since May 22, meaning their astonishing unbeaten run comes to an end at 23 games, and they are now level with Porto on four points.
On the pitch, Copenhagen's players started just as brightly and Federico Santander's effort from a tight angle drew a smart save from the legs of Kasper Schmeichel.
The England international's deep cross from the left found Slimani at the far post and he nodded back inside for Mahrez, who cleverly turned the ball beyond Olsen from just outside the six-yard box.
Leicester believed they had doubled their advantage in the 67th minute when Slimani scored at the second attempt, the striker having seen his initial effort from Marc Albrighton's cross kept out by a combination of Olsen and the woodwork.
The referee's assistant quickly cut short the celebrations by flagging for offside, although replays suggested it was a tight call by the official.
The decision would have proved costly were it not for Schmeichel's reflexes, the Denmark international producing a superb save to deny countryman Cornelius from grabbing a 90th-minute equaliser.
